The invention relates to a gas generator.
Gas generators with an outer housing made of plastic have already been proposed and tested. In an outer housing of this type, there may be accommodated a pyrotechnic propellant charge and an igniter having its own igniter housing. It is an aim of the invention to provide a gas generator in which the sealing of the igniter in the plastic housing can be carried out in a simple manner so as to prevent the entry of moisture.
This is achieved in a gas generator which comprises an outer housing made of plastic, in which a pyrotechnic propellant charge and an igniter having its own igniter housing are accommodated. The igniter housing consists at least partially of plastic and is welded with the outer housing. The welding on of the igniter took place hitherto always only via metallic sections thereof, but not via sections of plastic. Through the invention, it becomes possible to unify the connection of the individual parts in the production of the gas generator by the welding of plastic being provided exclusively. Thus the igniter, which is usually ordered as a separately delivered part, can be simply welded into a housing part, and the housing, in so far as it consists of several parts, is then likewise closed by welding. Through the welding of the plastic, connections can be realized which are gas-tight and are protected from the entry of moisture, without the intercalation of additional sealing elements.
According to the preferred embodiment, the welding is an ultrasonic welding, i.e. a very favorably priced method.
Furthermore, the igniter preferably has electric connecting lines which extend through at least one opening in the gas generator outer housing. The igniter housing seals the opening after welding, so that no moisture can penetrate into the interior of the gas generator and no gas can emerge via the opening on activation of the gas generator. The igniter, more precisely the section of the igniter which is made of plastic and is welded to the outer housing, therefore has a dual function, because it also serves as closure for the opening for the passage of the connecting lines. A sealing of the openings by potting, as was always proposed hitherto in the prior art, can be dispensed with.
The outer housing preferably has a cup-shaped receiving part for the propellant charge and a cover to which the igniter is welded. The receiving part and the cover are likewise welded to each other, so that the same type of connection is selected.
A radial gap between the receiving part and the cover can be provided, into which a projection of the igniter protrudes, whereby the latter is additionally secured in position. Possibly, this securing in position can absorb additional forces, so that the weld seam igniter/outer housing does not have to receive the entire mechanical stress.
A particularly simple embodiment is distinguished in that contact sleeves are embedded in the cover, the igniter being provided with contact pins that are introduced into the contact sleeves. The contact sleeves are in addition preferably connected with connecting cables on their outer ends. Thus, for example, a simple electrical contacting can be achieved in that the contact sleeves, embedded into the cover by injection-molding or potting, together with the connecting lines and the cover form a preassembled unit, into which then only the igniter has to be inserted from the inside.